1. Field of the Invention
The current invention relates to a surgical device and, more specifically, to a surgical device containing one or more design features that allow to the device to be used safely.
2. Discussion of the Background
Most existing trocars used for endoscopic surgical procedures are incapable of truly effective prevention of injuries to internal organs during insertion and manipulation of the trocar. Despite intensive efforts to improve present trocar designs, the results are still dismal. Present procedures frequently injure internal organs, and the resulting wounds are sometimes serious or even fatal. The need for safer trocars is thus imperative, especially given that endoscopic surgical procedures are likely to become more widespread in the future.
Endoscopic or minimally invasive surgery presents an opportunity to improve present surgical procedures and instrumentation comparable only to the revolutionary effect of the introduction of anesthetics in the 19th Century.
Most present day trocars utilize a tip xe2x80x9cshieldxe2x80x9d, or cover, for the cutting edges which is usually deployed immediately after penetration of the body cavity has taken place. Such a penetration is fraught with danger of injury to internal organs. However careful a surgeon may be during penetration of the body cavity, the resistance to penetration drops at the last instant prior to damage to the internal organs. This sudden drop in the resistance to penetration is called a xe2x80x9cplunge effectxe2x80x9d and occurs prior to any safety feature deployment. In some trocars, the penetration is controlled in some fashion, either taking place in small increments or under some form of approximate direct observation, estimate, or monitoring. In all cases, however, the designs result in much of the piercing tip being inserted to a dangerous depth before any protecting devices is deployed. This is perhaps not surprising since, after all, a hole must be made before any protection is deployed.
Since in most cases delicate organs are very close to the inside of the skin layer being pierced, it is advisable to perform the penetration after internal cavities have been filled with carbon dioxide to minimize the danger of accidental injury due to contact with the sharp piercing tip or the cutting edges of the instrument. In most cases, however, the force required for penetration and the elastic nature of the muscular layer cause a severe depression at the surgical portal, therefore bringing the penetrating tip of the instrument closer to the internal organs. In some of those cases, the sudden penetration of the cavity wall and the rapid drop in resistance allow the instrument to be propelled far deeper than desired or is possible to control. Furthermore, friction between the tissue walls and any protective device retards the deployment of the protective device, and an injury almost inevitably occurs.
Accordingly, one object of this invention is to insure that such events be avoided through a surgical device in which a penetrating tip or cutting edge(s) of the instrument be kept, at all times, sufficiently distant from delicate tissues. Thus, even under dynamic conditions, the probability of injury will be reduced.
A further object of this invention is to provide a surgical device wherein insufflation fluid can be driven into a patient during penetration of the body cavity by the surgical device to drive the internal organs away from the surgical device during penetration. The insufflation fluid of the present invention can either be supplied from an external pressurized reservoir, or compressed (and hence gathered) during penetration of the body cavity by the surgical device.
A further object of the invention is to provide a surgical device that contains one or more cutting edge that provides low frictional forces between the cutting edge and tissue during penetration of the body cavity, thus reducing the force needed to drive the surgical device into the body cavity.
A further object of the invention is to provide a surgical device that includes a protective device that deploys while remaining substantially out of contact with tissue, thus reducing frictional forces between the protective device and ensuring a controlled and advantageous deployment.
A further object of the invention is to provide a surgical device that includes a protective device such as safety guards, wherein the guarding elements have an apex and the angle subscribed at the apex is smaller than the angle subscribed by the blades or cutting elements of the surgical device, thus insuring progressive coverage of the blades or cutting elements during deployment of the protective device.
A further object of this invention is to provide a surgical device with a grip mechanism that allows convenient gripping and twisting of the surgical device during penetration of the body cavity.
A further object of this invention is to provide a surgical device that includes a locking system that prevents accidental reuse of the cutting elements after the tip has been used.
It is therefor desired that this invention, in general, improve surgical safety.
These and other objects of the invention are achieved by a surgical device such as a trocar tissue penetrator including a set of thin planar arrow-pointed cutting blades joined at a cutting point coaxial and within a hollow cylinder penetrator and having the cutting edges converge at a cutting angle at the cutting point. The back outside of the set of cutting blades can be fixed to the inside of the hollow cylinder penetrator with the cutting edges fully protruding. The hollow cylinder can have its front end slotted and each segment pointed in a triangular shape and bent to fit between the blades and having its edges substantially parallel to the edges of the protruding blades but axially recessed behind such edges to act as a tissue expander to prevent contact between inside moving guards and the outside tissue. The slots between the triangularly shaped bent section tissue expanders at the end of the hollow cylinder penetrator can be wide enough to permit the passing between them and the sides of the cutting blades of a guard sheet at least as thick as the blades. A set of elongated axially bent sheet guards can be set to slide freely within the space between the sides of the cutting blades and the triangular bent segments of the hollow cylinder and having their frontal end with a tip angle profile substantially more acute than the adjacent angle of the blade edges and terminating in a very small dull round tip. The angular frontal edges of the bent sheet guards can have shallow angle ends and curving slowly toward the edges so that at no time their angle exceeds that of the adjacent cutting edges. The elongated bent sheet guards inserted between the cutting blades and the triangularly bent segments of the hollow cylinder can be attached at their opposite end to a stem which is urged toward the frontal cutting edges by a coil spring.
The advantageous characteristics of this surgical device include, e.g., the following:
a multiple system of sharp planar knife edges that practically eliminate lateral friction and provide a reduced resistance to penetration, thereby reducing the penetration xe2x80x9cplunge effectxe2x80x9d and tissue springback.
a mechanical tissue protection device that includes a series of thin plastic guards sliding along the sides of the planar knives and, in a preferred embodiment, having an angle between their edges smaller than that of the cutting knife edges. It can then be shown that, with proper contouring of such plastic guard edges, it is possible to provide complete guarding between the cutting edges and the surrounding tissues from the very start of the penetration, and to do so in a truly progressive manner, without jerks or discontinuities. The progressive guarding action that results from the smaller angle between the sides of the guards than the angle between the edges of the cutting blades allows the guards to plunge into the tiny opening made by the cutting tip and instantly surround it, thereby preventing injury to internal organs during the most crucial instant of the trocar insertion. Therefore, guarding action takes place in a truly progressive manner in which, as the cutting blades continue expanding the tiny initial opening, the guards progressively advance keeping the cutting edges constantly covered outside the penetrating region and isolated from internal organs until the penetration is completed and the cannula fully inserted;
one or more fixed conical deflectors to expand the cut tissue passage leaving the guards to contact tissue only at their tips, thus isolating the guards from friction against the tissue at the sides of the point of penetration. Therefore, as soon as even a minute opening is made at the tip by the cutting blades, the guards instantly plunge into the opening and prevent the blade tips from any contact with internal organs. Thus, using tissue expanders outside the guards prevents friction between the guards and the tissue, which would retard the deployment action. The use of this tissue expander allows the safety device to function without restriction, thereby eliminating one of the major deficiencies of existing trocars. In other words, the dynamic response of the guards is inherently much faster than the rate of penetration of the blades. As a result, cutting edges are never dangerously exposed to, contact with internal organs, however fast the penetration rate may be;
an insufflation passage configured to transport fluid into the body cavity during penetration. The insufflation passage can be pressurized either using an external reservoir or by compressing gas contained in the passage during penetration. Once an initial penetration of the epithelium has been made, fluid from the insufflation passage will drive the internal organs away from the cutting edge(s). In the case of an external carbon dioxide gas reservoir, a carbon dioxide gas valve is opened, thereby pressurizing the penetrator tubular body. Under such pressurization, since the front is enclosed by tissue, the cutting tip penetrates the tissues while the gas is prevented from exhausting, but as soon as the most minute opening starts to appear at the tip, the gas expands suddenly into the opening and forcibly deflects delicate internal organs away from the tip of the cutting surface while simultaneously the guard tips are forced through the opening by their spring. The use of a pressurized fluid (or gas) tissue deflector thus creates an organ-free zone in front of the cutting blade tips at the instant of the incipient penetration, even before the guard tips plunge into the opening. It must also be pointed out that a sudden gas expansion can also aid the deployment of the guards since the flow occurs between the cutting blades and the conical expanders, precisely where guards may be located. It could almost be said that the guards are spit out by the fluid flow. This increases the velocity of their deployment and hence the overall safety of the surgical device;
a locking system for the guards, which is located at the proximal end of the instrument, prevents accidental reuse of the cutting features after the tip has been safely introduced for the first time. The locking system for the trocar guards includes a locking cylinder attached to a locking button supported by a leaf spring and inserted into a socket. The cylinder has a conical tip and a circumferential groove at the bottom and can be depressed by way of the button and engaged by the groove into a U shaped spring that will hold it down permitting it sliding motion until it comes out of the U shaped spring and is ready for locking again on its return to the initial position. If a reset action is desired it is necessary to push hard downward against the locking button and deliberately reset it for another cycle. Since the locking button is located deep within a recess at the proximal section of the handle, it demands some effort to reach and actuate, and thus it is difficult to accidentally reset.
an ergonomic design which facilitates handling. The proximal hemispherical knob nestles easily into the hollow of the hand while the index and middle fingers control rotation by gripping the side horns, thereby permitting push, pull, rotation, and tilting in a very natural and comfortable manner.